mldversion

The MLD package makes directory foo.mld turn into module Foo

The contents of module Foo are the modules that can be "found" in directory foo.mld and recursively in its subdirectories,
down to other directories of the form bar.mld:
Bar will be a submodule of Foo, and the recursive search for Foo's modules stops there.
The contents of bar.mld will then be used to determine the submodules of Foo.Bar.
Hence, the following source tree